In this proposal, we will investigate a novel approach for delivery of a DNA vaccine to mucosal surfaces. Our initial efforts will focus on the use of a plasmid containing the influenza HA gene. The HA gene in plasmid DNA vectors has been found to be expressed at high levels and capable of effective induction of specific immune responses following intramuscular or gene gun delivery, and sensitive assays are available for analysis of HA expression as well as detection of immune responses to the expressed protein. In addition, influenza remains a major public health problem and there is a great need for development of improved measures to control influenza infection, and mucosal immune responses represent the unique host defense mechanism which confers protection against infection by the virus. The specific aim of the Phase 1 proposal is to incorporate fusogenic F and HN proteins of human parainfluenza virus into lipid vesicles containing the influenza HA plasmid DNA, as an approach to enhance delivery of this DNA vaccine plasmid. Since these parainfluenza viruses exhibit tropism for respiratory epithelial cells and are able to deliver their viral genomes to such cells by a membrane fusion mechanism, the incorporation of the DNA vaccine into vesicles containing their fusogenic surface proteins wold be expected to enhance delivery of the vaccine. The effectiveness of DNA vaccine delivery and expression will be evaluated by analysis of protein expression, its localization in specific cell types, and by assays of virus specific immune responses. Proposed commercial applications: The proposed research could lead to the development of a novel approach foe the delivery of a DNA vaccine to the respiratory tract. This approach has great potential commercial advantages for the development of vaccines for the control of infections by respiratory viruses as well as other microbial agents.